Energy Capture and Early Cell Division Concepts

Apuntes

Photosynthesis is the process of turning sunlight into food. The general chemical equation for photosynthesis is: $$6H₂O(l) + 6CO₂(g) + \text{light energy} \rightarrow C₆H₁₂O₆(aq) + 6O₂(g)$$ Photosynthesis occurs in two stages: the light-dependent phase and the light-independent phase. The light-dependent phase involves capturing energy from sunlight. Chlorophyll, a pigment in the chloroplasts, absorbs energy from sunlight to energize electrons. This phase occurs in the thylakoids, which are green sacs within the chloroplasts, organized into structures called grana. During this phase, the electron transport chain increases the concentration of H⁺ ions in the thylakoid and decreases the concentration of H⁺ ions in the stroma. This process is essential for ATP production. The light-independent phase, also known as the Calvin cycle, occurs in the stroma of the chloroplasts. In this phase, carbon dioxide (CO₂) is attached to a 5-carbon molecule called ribulose bisphosphate (RuBP) by the enzyme RuBisCO, forming an unstable 6-carbon compound. This compound quickly splits into two 3-carbon molecules of 3-phosphoglyceric acid (3PG). During the reduction phase, 3PG is converted into glycera...